In a manufacturing process of silicon single crystals, polycrystalline silicon raw materials charged in a crucible are heated by a heater to form a silicon melt, and silicon single crystals are grown by pulling the crystals from the silicon melt in accordance with the Czochralski (CZ) method. Silicon wafers are manufactured by slicing (cutting) the silicon single crystal which has been manufactured by the above-described method, and devices such as integrated circuits or the like are formed on the silicon wafer.
There is a trend for increasing the diameter of the silicon single crystal so as to form large numbers of circuits on a single silicon wafer. On the other hand, the increasing diameter of the silicon single crystal cause problems in a single crystal growth technique, for example, reducing oxygen concentration in the single crystal, stabilizing qualities, and improvement of production yield. As a solution for such problems, there is a method to realize reduction of oxygen concentration in the single crystal and stabilizing the crystal growth by the application of a HMCZ (Horizontal magnetic field applied CZ) technique in which a horizontal magnetic field is applied during the CZ crystal growth.
In another known method, a solid-liquid interface constituting the boundary between the silicon single crystal is controlled to have a upwardly convex shape protruding towards the single crystal side, thereby increasing axial thermal gradient in the single crystal in the vicinity of the solid-liquid interface, and obtaining the effect of in-plane homogeneity (Japanese Unexamined Patent Application, First Publication, No. 2001-158690).